A fundamental goal of neuroscience is to understand how neural circuitry carries out the computations that transform raw sensory signals into behavior. Current understanding is limited by available techniques for recording neural activity in awake, behaving organisms. At one end of the range of spatial scales, microelectrode arrays provide excellent temporal resolution of single neuron activity, but can only sparsely sample the local neuronal population. At the other end, functional magnetic resonance imaging has poor resolution in both space and time, and records neuronal activity only indirectly through blood flow. Optical imaging promises to revolutionize neuroscience by bridging this gap and offer minimally-invasive, direct recording of neural activity at single cell resolution in the intact working brain. Optical imaging of neural activity, however, has yet to deliver the ultimate prize of recording the activity of many individual neurons in real time throughout the depth of a brain structure such as the cerebral cortex. Achieving such a goal will require the coordinated effort of experts from disparate backgrounds, including neuroscientists, optical engineers, biochemists and molecular biologists. The obvious need to bring such experts together in dialogue is the central motivation for the 27th Symposium of the Center for Visual Science (CVS), entitled "Photons and Neurons", scheduled for June 4th- 6th, 2010 at the University of Rochester. The goal is to bring together scientists who develop and use imaging methods and provide a platform to exchange ideas, identify pressing neurobiological questions, discuss current limitations, and develop possible solutions. Individual sessions will cover the following topics: (1,4) Imaging CNS circuits, (2) Advances in Optical imaging, (3) Imaging the retina, (5) Controlling neurons with light. We expect that the Symposium will attract researchers representing multidisciplinary approaches ranging from neural coding and primate neurophysiology to optical engineering and molecular biology. We are particularly interested in attracting younger neuroscientists and optical engineers. To that end, we plan to award ten travel fellowships to graduate students interested in attending the meeting and provide them with an opportunity to present their work in a poster session. PUBLIC HEALTH RELEVANCE: Optical imaging of neural activity has yet to deliver the ultimate prize of recording the activity of many individual neurons in real time throughout the depth of a brain structure such as the cerebral cortex. Achieving such a goal will require the coordinated effort of experts from disparate backgrounds, including neuroscientists, optical engineers, biochemists and molecular biologists. The obvious need to bring such experts together in dialogue is the central motivation for the 27th Symposium of the Center for Visual Science (CVS), entitled "Photons and Neurons."